Bellcore Personal Access Communications System (PACS) provides the feature of using a single time-slot for two independent calls by the same user. This feature allows a simultaneous voice and data call from a single subscriber unit. This paper compares the performance of a PCS system with voice/data self-subrating (SSR) with a system without self-subrating (NSSR). We show that for the ranges of the input parameters we study, the blocking probability for NSSR is 76% higher than for SSR. For a PCS system engineered at 1% blocking probability, SSR carries 15.3% more offered load than NSSR.